PHOTOELASTIC VISUALIZATION OF ULTRASOUND GENERATED BY PULSED-LASER

We applied the dynamic photoelastic technique to visualize the ultraso und generated in a glass sample by an Nd:YAG pulsed laser. When a lase r pulse was incident on the surface of the glass sample covered by thi n layer of black ink, narrow pulses of longitudinal, shear, and surfac e acoustic waves were seen in the sample. The photoelastic picture als o showed that the directivity patterns of ultrasound generated in the present case qualitatively agree with the theoretical prediction for t he case of a normal surface-acting force.